An ever increasing problem, particularly in urban areas, is the disposal of the solid and liquid wastes produced both by individuals and industries. Such waste materials can take a great variety of different forms and sizes and have a corresponding variety of different chemical compositions. For example, such wastes can be found to include paper, wood, metal, plastic, glass, garbage, grease, oils, soil and the like, either alone or in combined form. Certain of these materials break down easily on the application of heat (e.g., wood, paper and certain plastics), whereas others such as inerts, metals, earth and the like, for example, are relatively unaffected by heat except at very high temperatures. In any event, all of the waste materials, unless they can be reclaimed or recycled for future use, must be disposed of, since their presence in large accumulation is hazardous to the health and well being of humans.
One approach to waste disposal that has been frequently relied upon in the past is to utilize the waste materials for landfill. This, of course, presupposes the availability of the requisite amount of land suitable for this purpose. It is clear that many of the urban areas are simply not able to use this technique, either through a general shortage of available land for this purpose, or due to the fact that the distance of the available landfill areas from the waste disposal sources is prohibitively great.
Another technique which has been relied upon extensively in the past, but is no longer acceptable, particularly in urban areas, is that of incinerating the combustible waste materials. Incineration or open air combustion of waste materials, unfortunately, produces large amounts of polluting gases and gases containing suspended materials. In fact, most urban communities have now promulgated very strict ordinances controlling the release of such polluting materials into the atmosphere, and for this reason, incineration is no longer a feasible approach to waste disposal.
Still other approaches have included combinations of landfilling and incineration, as well as changing the form of the waste material by cutting or sizing to make it more amenable to further processing. In addition, salvage operations are frequently conducted to remove certain items from the waste batch for recycled use. Examples of a few such materials commonly reclaimed are metals, returnable bottles, certain types of plastic containers, rubber tires, paper base materials and apparatus such as refrigerators, washers, dryers or other appliances. The latter items not only may possess recyclable or resale value in themselves, but also could pose a handling problem by jamming or otherwise making the disposal equipment inoperative.
In all facilities where combustion oxidation has been used for waste disposal, it has been necessary in the past to provide additional fuel to achieve pyrolysis or incineration, e.g., oil or natural gas. This, of course, adds to the overall expense of a waste disposal operation, and, in many cases, raises it to prohibitively high levels. Also, of course, with the increasing shortage of fossil fuels, waste disposal systems based upon the need for use of such high quality fuels are neither economically feasible, nor, perhaps, even supportable at this time.
Certain types of solid waste materials are especially difficult to handle and in the past have necessitated special handling. For example, wood, as obtained from a demolished house or building, may not only come in rather large pieces of varying shape, but also has a high BTU output which must be taken into account in any process involving disposal by combustion oxidation. As will be described herein, the subject invention is particularly adaptable for the disposal of wood, and, in fact, utilizes it as a basic fuel for the heat destruction of other waste materials.
Still further, there are many inflammable liquid waste materials which must be disposed of. For example, there are so-called "light ends" produced in refineries as well as used solvents and cleaning agents from the dry cleaning industry which are highly inflammable and pose a unique disposal problem. In the past, it was considered necessary to store and dispose of such liquids spearately, due to their high volatility.